A capacitor having a sufficient capacitance in a limited area has been demanded as a semiconductor device has been highly integrated. The capacitance of the capacitor may be proportional to a surface area of an electrode and a dielectric constant of a dielectric layer and may be inversely proportional to an equivalent oxide thickness of the dielectric layer. Thus, to increase the capacitance of the capacitor in a limited area, a three-dimensional capacitor may be formed to increase the surface area of the electrode, the equivalent oxide thickness of the dielectric layer may be reduced, and/or a dielectric layer having a high dielectric constant may be used in the capacitor.
To increase the surface area of the electrode, a height of a lower electrode (or a storage electrode) may be increased, an effective surface area of the lower electrode may be increased using a hemi-spherical grain (HSG), and/or an inner surface area and an outer surface area of one cylinder storage (OCS) electrode may be used as the surface area of the lower electrode. In addition, the dielectric layer having the high dielectric constant may include a metal oxide layer (e.g., TiO2 or Ta2O5) or a ferroelectric having a perovskite structure (e.g., PbZrTiO3 (PZT) or BaSrTiO3 (BST)).